Solve 2025-03

2025/03/index.ts

@@ -0,0 +1,45 @@
+import { sumArray } from '../../utils/array.ts';
+
+function findHighestDigit(digits: number[], start: number, end: number) {
+  let highest = 0;
+  let highestI = start;
+
+  for (let i = start; i < digits.length - end; i++) {
+    if (digits[i] > highest) {
+      highest = digits[i];
+      highestI = i;
+    }
+  }
+
+  return highestI;
+}
+
+function findHighestNumber(row: string, size: number) {
+  const rowSplit = row.split('');
+  const digits = rowSplit.map(Number);
+
+  const highest: number[] = [];
+  for (let i = 0; i < size; i++) {
+    const highestDigit = findHighestDigit(
+      digits,
+      (i > 0 ? highest[i - 1] : -1) + 1,
+      size - i - 1
+    );
+
+    highest.push(highestDigit);
+  }
+
+  return Number(highest.map((key) => rowSplit[key]).join(''));
+}
+
+export function solveFirst(input: string): number {
+  const rows = input.split('\n');
+
+  return sumArray(rows.map((row) => findHighestNumber(row, 2)));
+}
+
+export function solveSecond(input: string): number {
+  const rows = input.split('\n');
+
+  return sumArray(rows.map((row) => findHighestNumber(row, 12)));
+}